8.14.5 Replication Master Thread States

The following list shows the most common states you may see in
the State column for the master's
Binlog Dump thread. If you see no
Binlog Dump threads on a master server, this
means that replication is not running—that is, that no
slaves are currently connected.

Sending binlog event to slave

Binary logs consist of events, where an
event is usually an update plus some other information. The
thread has read an event from the binary log and is now
sending it to the slave.

Finished reading one binlog; switching to next
binlog

The thread has finished reading a binary log file and is
opening the next one to send to the slave.

Has sent all binlog to slave; waiting for binlog to
be updated

The thread has read all outstanding updates from the binary
logs and sent them to the slave. The thread is now idle,
waiting for new events to appear in the binary log resulting
from new updates occurring on the master.